Ribonucleic acids (RNA) are the subject of ongoing research in a basic science context as well as in a clinically-directed context where RNAs are used as therapeutic agents, drug targets, and informative biomarkers. New ventures have been formed around the use of RNAs as research tools, therapeutics, and/or diagnostics, and many existing companies have established RNA-related research and new product initiatives. In addition, there has been a significant increase in knowledge of previously uncharacterized noncoding RNAs over the past decade, and structure/function studies of such RNAs are ongoing. Such studies often involve the use of chemical RNA synthesis techniques to obtain RNAs under investigation. However, such techniques are often limited by low yields, including at lengths as short as 50 bases.
T7-related RNA polymerases, such as those from the bacteriophages T7, T3, SP6, or K11, and others are frequently used to synthesize RNA in vitro and in vivo. T7-related RNA polymerases may be used to obtain RNAs of any length in high yield and purity. Expression plasmids used in molecular biological research routinely include promoters for these polymerases (e.g., T7, T3, SP6 promoters) in their flanking sequences, and early references reporting protocols for large scale in vitro synthesis of RNA using such polymerases are widely cited.